Log CFU Reduction Research Articles

1550. PK-PD Relationship and PK Driver of Efficacy of the Novel Antibacterial Lysin Exebacase (CF-301) in Pre-Clinical Models

BackgroundExebacase (CF-301) is a novel lysin with rapid bacteriolytic and anti-biofilm activity against S. aureus, pronounced synergy with antibiotics and low propensity for resistance. Exebacase has undergone Phase 1–2 trials. This work was to develop pharmacokinetic (PK) model in animal and determine the relationship between exebacase exposure and efficacy in animals.MethodsPK data in 592 animals (4 species) included in population PK model. A range of linear and nonlinear mammillary models with allometric scaling fitted to the PK data using NONMEM and the most parsimonious model was selected by improvement in objective function value (P < 0.01). To evaluate efficacy, 349 animals with 177 mice (neutropenic thigh infection) and 172 rabbits (aortic valve infective endocarditis were treated with exebacase in addition to suboptimal doses of daptomycin (DAP). Full PK profiles were simulated for individual animals. Fifty-nine dosing regimens of exebacase in mice (0–90 mg/kg) and 18 regimens in rabbits (0–1.4 mg/kg) with q24h, q12h and q8h frequencies. Relationship between AUC/MIC, Cmax/MIC, T> MIC, and log-CFU was examined using a range of functions by comparing residual standard error (RSE).Results3-compartment model with allometric scaling best described the PK data and was validated by bootstrap and Goodness of Fit. Maximum drop in log10CFU/g in target tissues was at AUC/MIC< 0.2 for exebacase when added to DAP that was associated with CF reduction of -5 logs in rabbits (Figure (a)) with similar magnitudes in cardiac vegetations, kidney and spleen, and -4 logs in mice (Figure (b)). Treatment with DAP alone had log10CFU reduction of -1 in mice; and -2 in rabbits. AUC/MIC was an appropriate predictor of CFU reductions.ConclusionPK model adequately described the data for 4 animal species. Exebacase addition to DAP has a synergistic effect on efficacy measured by CFU reductions in target tissues in the animal models. Results support previously presented determinations of AUC/MIC as predictor of efficacy. Maximum reductions in CFU in rabbits and mice were observed at AUC/MIC ratios <0.2. These results further indicate that rabbit is the most appropriate efficacy model with MICs and antibacterial activity reflective of previously reported observations in human serum. Disclosures All authors: No reported disclosures.

Degradation of chlorpyrifos and inactivation of Escherichia coli O157:H7 and Aspergillus niger on apples using an advanced oxidation process

Chlorpyrifos is a widely used insecticide in apple production but there are concerns that residues ingested by consumers can lead to chronic neurological conditions. In the following, a method based on Advanced Oxidation Process (AOP) was validated for the degradation of chlorpyrifos on apples and inactivating Escherichia coli O157:H7, along with Aspergillus niger spores. AOP is a process that generates free-radicals from the UV-C (at 254 nm) mediated degradation of hydrogen peroxide thereby leading to highly oxidative species. By using Response Surface Methodology (RSM) it was found that the degradation of chlorpyrifos was primarily dependent on UV-C dose and synergistically enhanced by applying the hydrogen peroxide at temperatures up to 66 °C. However, the degradation of chlorpyrifos was independent on the hydrogen peroxide concentration up to 6% v/v. Maximal degradation of chlorpyrifos on apples was achieved through an AOP treatment applying 68.4 kJ/m2 UV dose and 1.22% v/v H2O2 at 66 °C that resulted in 118 μg degradation (representing 59% of the original level) of the pesticide with <20 ppb accumulation of the degradative photoproduct, CPY-O. The same treatment supported a >6.6 log CFU reduction in E. coli O157:H7 and >4.7 log CFU reduction of A. niger spores. Applying UV alone in the case of E. coli O157:H7 or hydrogen peroxide alone against A. niger spores supported a lower level of lethality compared to AOP. In conclusion, the study has demonstrated that an AOP based process can support the degradation of chlorpyrifos and address microbiological hazards associated with apples.

The inoculum effect of Escherichia coli expressing mcr-1 or not on colistin activity in a murine model of peritonitis

ObjectivesColistin often remains the last resort antibiotic active against carbapenemase-producing Enterobacteriaceae. However, while in vitro inoculum effect has been reported, therapeutic relevance of this phenomenon remains questioned. MethodsTen E. coli strains were used that included the wild-type CFT073 and its transconjugant CFT073-MCR-1 and eight susceptible clinical isolates. Mice with peritonitis were treated for 24 h with colistin sulfate. Bacterial loads were determined in peritoneal fluid (PF) and spleen and colistin-resistant mutants were detected. ResultsMICs of colistin against the eight susceptible clinical strains and CFT073 ranged from 0.125 to 0.5 mg/L with an inoculum of 105 CFU/mL and from 2 to 4 mg/L with a 107 CFU/mL inoculum; 5/9 strains with an MIC of 4 mg/L were considered resistant according to EUCAST breakpoint (resistance, > 2 mg/L). When the bacterial load of wild-type CFT073 inoculated in mice increased from 107 to 108 CFU: i) mean log10 CFU reduction generated by colistin in PF and spleen decreased from 5.8/mL and 3.1/g, respectively, (p < 0.01) to 0.9/mL and 0.8/g, respectively (NS); ii) mice survival rate decreased from 15/15 (100%) to 6/15 (40%) (p = 0.017); and iii) proportion of mice with selection of colistin-resistant mutants increased from 4/15 to 15/15 (p < 0.01). These results were comparable to those obtained when peritonitis was produced with a 107 CFU bacterial load of E. coli CFT073 expressing mcr-1, for which the mean log10 CFU reductions were 3.5/mL and 0.6/g in PF and spleen, respectively (NS), and survival rate was 8/15 (53%) (p < 0.01 versus survival of mice infected with wild-type CFT073). ConclusionsPhenotypic colistin resistance in wild-type E. coli due to an increase in inoculum size had a therapeutic impact in mice with peritonitis that was comparable to that observed when the mcr-1 gene was expressed.

Ultrasound treatment combined with fumaric acid for inactivating food-borne pathogens in apple juice and its mechanisms

The purpose of this study was to evaluate the synergistic bactericidal efficacy of combining ultrasound (US) and fumaric acid (FA) treatment against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in apple juice and to identify the synergistic bactericidal mechanisms. Additionally, the effect of combination treatment on juice quality was determined by measuring the changes in color, pH, non-enzymatic browning index, and total phenolic content. A mixed cocktail of the three pathogens was inoculated into apple juice, followed by treatment with US (40 kHz) alone, FA (0.05, 0.1, and 0.15%) alone, and a combination of US and FA for 1, 2, 3, 4, and 5 min. Combined US and 0.15% FA treatment for 5 min achieved 5.67, 6.35, and 3.47 log reductions in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, with the 1.55, 2.37, and 0.57 log CFU reductions attributed to the synergistic effect. Although the pH value slightly decreased as FA increased, there were no significant (P > 0.05) differences in color values, browning indices, and phenolic content between untreated and treated samples. To identify the mechanism of this synergistic bactericidal action, membrane integrity, malfunctions in the membrane efflux pump, and intracellular enzyme activity were measured. The analyses confirmed that damage to the cell envelope (membrane integrity and efflux pump) was strongly related to the synergistic microbial inactivation. These results suggest that simultaneous application of US treatment and FA is a novel method for ensuring the microbial safety of apple juice.

Induction of mycobacterial protective immunity by sublingual BCG vaccination

Tuberculosis (TB) remains a tremendous global health problem, with 1/4 of the world’s population infected and causing > 1 million deaths annually. Intradermal Bacillus Calmette-Guérin (BCG) vaccine given during infancy protects against severe forms of acute disease but does not prevent chronic infection or development of pulmonary TB. TB vaccine mucosal targeting potentially could induce mucosal resident immune cells with increased protective capacity against pulmonary infection and disease. Sublingual (SL) administration of vaccines may be an optimal mucosal delivery platform based on the high absorptive capacity of this mucosal surface, the extensive lymphoid tissue, and published preclinical studies demonstrating efficacy of SL vaccination against other pathogens. To this end, we performed preliminary testing of sublingual TB vaccines. Vaccination of mice with SL BCG elicited potent mycobacteria-specific T cell responses which persisted 16 weeks post-immunization. The magnitudes of the T cell responses were similarly induced after sublingual, intranasal, and subcutaneous BCG vaccination. Interestingly, serum mycobacteria-specific antibody responses and systemic recovery of BCG post-vaccination were lower after SL BCG compared with systemic BCG immunization. However, more importantly, SL BCG vaccinated mice were significantly protected against an aerosolized virulent M. tuberculosis challenge (P < 0.0001 compared to unvaccinated mice). Furthermore, this protection was long-lived, persisting for 16 weeks with >1 log CFU reduction compared with naïve challenged mice in both lungs and spleens (P < 0.0001 and P < 0.0028, respectively). These exciting results provide strong support for further studies exploring the mechanisms of protective immunity induced by sublingual BCG vaccination.

Characterization of efficacy and flow in a commercial scale forced air ozone reactor for decontamination of apples

Air flow characteristics and decontamination efficacy are investigated within a forced-air ozone reactor designed to control Listeria monocytogenes on apple fruit. The commercial reactor introduced an air-ozone mix through a column of apples (540 kg contained within two bins; dimensions 1.21 m × 1.21 m × 0.72 m) for a defined air velocity and time period. The apple bed had high porosity (ɛ = 0.533) with a corresponding low pressure differential (10 Pa/m). Incoming air flowed through the ozone generator with low air velocities (0.022 m/s) introducing 39 ppm of the antimicrobial gas into the chamber. As the air flow was increased to 0.147 m/s, the corresponding ozone concentration at the entry point into the chamber dropped to 4 ppm through dilution. At the lowest air velocity the log reduction of Lactobacillus (surrogate bacteria for Listeria) inoculated onto applies varied between 0.5 and 2.5 log CFU across the bed, compared to 1.6 to 2.5 log CFU reductions that were observed at air velocities greater than 0.088 m/s. It was found the homogeneity in decontamination efficacy across the bed was primarily dependent on the applied air velocity with ozone concentration (4–39 ppm) and treatment time (5–40 min) being less influential.

Enzyme responsive copolymer micelles enhance the anti-biofilm efficacy of the antiseptic chlorhexidine

Staphylococcal biofilms cause many infectious diseases and are highly tolerant to the effects of antimicrobials; this is partly due to the biofilm matrix, which acts as a physical barrier retarding the penetration and reducing susceptibility to antimicrobials, thereby decreasing successful treatment outcomes. In this study, both single and mixed micellar systems based on poly vinyl caprolactam (PCL)-polyethylene glycol (PEG) copolymers were optimised for delivery of chlorhexidine (CHX) to S. aureus, MRSA and S. epidermidis biofilms and evaluated for their toxicity using Caenorhabditis elegans. The respective polyethylene glycol (PEG) and poly vinyl caprolactam (PCL) structural components promoted stealth properties and enzymatic responsive release of CHX inside biofilms, leading to significantly enhanced penetration (56%) compared with free CHX and improving the efficacy against Staphylococcus aureus biofilms grown on an artificial dermis (2.4 log reduction of CFU). Mixing Soluplus-based micelles with Solutol further enhanced the CHX penetration (71%) and promoted maximum reduction in biofilm biomass (>60%). Nematodes-based toxicity assay showed micelles with no lethal effects as indicated by their high survival rate (100%) after 72 h exposure. This study thus demonstrated that bio-responsive carriers can be designed to deliver a poorly water-soluble antimicrobial agent and advance the control of biofilm associated infections.

Zwitterionic Nanocellulose-Based Membranes for Organic Dye Removal.

The development of efficient and environmentally-friendly nanomaterials to remove contaminants and pollutants (including harmful organic dyes) ravaging water sources is of major importance. Herein, zwitterionic nanocomposite membranes consisting of cross-linked poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and bacterial nanocellulose (BNC) were prepared and tested as tools for water remediation. These nanocomposite membranes fabricated via the one-pot polymerization of the zwitterionic monomer, 2-methacryloyloxyethyl phosphorylcholine, within the BNC three-dimensional porous network, exhibit thermal stability up to 250 °C, good mechanical performance (Young’s modulus ≥ 430 MPa) and high water-uptake capacity (627%–912%) in different pH media. Moreover, these zwitterionic membranes reduced the bacterial concentration of both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) pathogenic bacteria with maxima of 4.3– and 1.8–log CFU reduction, respectively, which might be a major advantage in reducing or avoiding bacterial growth in contaminated water. The removal of two water-soluble model dyes, namely methylene blue (MB, cationic) and methyl orange (MO, anionic), from water was also assessed and the results demonstrated that both dyes were successfully removed under the studied conditions, reaching a maximum of ionic dye adsorption of ca. 4.4–4.5 mg g−1. This combination of properties provides these PMPC/BNC nanocomposites with potential for application as antibacterial bio-based adsorbent membranes for water remediation of anionic and cationic dyes.

Nanocellulose-based antifungal nanocomposites against the polymorphic fungus Candida albicans

The design of functional materials capable of fighting fungal infections is of paramount importance given the intricate problem of multidrug-resistant pathogenic fungi. Herein, nanocomposites consisting of cross-linked poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride) (PMETAC) and bacterial nanocellulose (BNC) were prepared, characterized and tested towards the polymorphic fungus Candida albicans. The BNC three-dimensional network enabled the in-situ polymerization of the non-toxic and bioactive quaternary-ammonium monomer, which originated transparent nanocomposites containing 10 and 40 wt.% of cross-linked PMETAC. Furthermore, the nanocomposites exhibit UV–A and UV–B blocking properties, high water-uptake capacity, thermal stability up to 200 °C, good viscoelastic (storage modulus > 1.7 GPa) and mechanical (Young’s modulus ≥2.4 GPa) properties and are non-cytotoxic to human keratinocytes (HaCaT cells). The fungal inactivation reached a 4.4 ± 0.14–log CFU reduction for the nanocomposite containing only 10 wt.% of cross-linked PMETAC. Hence, these bioactive and non-cytotoxic materials can constitute potentially effective systems for the treatment of C. albicans infections.

Pharmacokinetic/pharmacodynamic target attainment analyses to support intravenous and oral lefamulin dose selection for the treatment of patients with community-acquired bacterial pneumonia.

ObjectivesLefamulin is a semi-synthetic intravenous (iv) and oral pleuromutilin antibiotic active against community-acquired bacterial pneumonia (CABP) pathogens. Pharmacokinetic/pharmacodynamic (PK/PD) target attainment analyses were carried out to evaluate lefamulin 150 mg iv q12h and 600 mg orally q12h under fed and fasted conditions for the treatment of patients with CABP.MethodsThe analyses undertaken used a population PK model based on Phase 1 PK data, non-clinical PK/PD targets for efficacy and in vitro surveillance data for Streptococcus pneumoniae (SP) and Staphylococcus aureus (SA), and Monte Carlo simulation. Percentage probabilities of PK/PD target attainment by MIC on day 1 were determined using median total-drug epithelial lining fluid (ELF) and free-drug plasma AUC:MIC ratio targets associated with 1 and 2 log10 cfu reductions from baseline.ResultsPercentage probabilities of attaining the total-drug ELF AUC:MIC ratio target for a 1 log10 cfu reduction from baseline for SP were ≥99.2% at the MIC90 of 0.12 mg/L and 96.7%, 82.1% and 96.3% for iv and oral dosing regimens under fed and fasted conditions, respectively, at the MIC99 of 0.25 mg/L. Percentage probabilities of attaining the free-drug plasma AUC:MIC target for the same endpoint at the SP MIC99 were 100% for each regimen. For the SA MIC90 of 0.12 mg/L and AUC:MIC ratio targets for the same endpoint, percentage probabilities were 92.7%–100% for iv and oral dosing regimens.ConclusionsThese data provide support for lefamulin 150 mg iv q12h and 600 mg orally q12h for the treatment of patients with CABP and suggest that doses may not need to be taken under fasted conditions.

Pharmacokinetics/pharmacodynamics of lefamulin in a neutropenic murine pneumonia model with Staphylococcus aureus and Streptococcus pneumoniae.

ObjectivesTo present results of preclinical studies that supported further development of lefamulin for treating patients with community-acquired bacterial pneumonia (CABP).MethodsThe effect of bovine lung surfactant on the antibacterial activity of lefamulin against Streptococcus pneumoniae and Staphylococcus aureus was determined by broth microdilution assay. In vitro accumulation of lefamulin was evaluated in J774 mouse macrophages. Pharmacokinetics was assessed in female BALB/c (Bagg albino) mice treated with subcutaneous lefamulin (35 or 70 mg/kg). In neutropenic lung infection experiments, BALB/c mice received intraperitoneal cyclophosphamide before challenge with single S. pneumoniae or S. aureus strains; subcutaneous lefamulin (1.25–160 mg/kg) was given twice daily post-infection. Hill models described relationships between AUC/MIC ratios and changes in log10 cfu.ResultsLung surfactant did not significantly increase lefamulin MIC values against test strains. Lefamulin uptake in macrophages was rapid (a plateau was reached in ∼3 h). In mice, distribution of lefamulin [plasma to epithelial lining fluid (ELF)] was rapid, showing an ∼2-fold increase in lefamulin exposure in the ELF during the 5.5 h period. Median plasma AUC/MIC ratios associated with 1 and 2 log10 cfu reductions from baseline were 1.37 and 2.15, respectively, for S. pneumoniae and 2.13 and 6.24 for S. aureus. Corresponding ELF results were 14.0 and 22.0 for S. pneumoniae and 21.7 and 63.9 for S. aureus.ConclusionsOverall, lefamulin displays desirable pharmacokinetic/pharmacodynamic relationships that are predictive of the clinical effectiveness of lefamulin and other antibacterial agents used to treat CABP.

Effect of thermal, high hydrostatic pressure, and ultraviolet‐C processing on the microbial inactivation, vitamins, chlorophyll, antioxidants, enzyme activity, and color of wheatgrass juice

AbstractThe comparative study determined the fate of vitamin C, chlorophyll, antioxidants, enzymes (polyphenol oxidase [PPO], peroxidase [POD]) and effect on color of wheatgrass juice processed by thermal, high hydrostatic pressure (HHP), or ultraviolet‐C light (254 nm; UV‐C) to inactivate Escherichia coli P36, Listeria innocua ATCC 51742, and Salmonella Typhimurium WG49. A thermal treatment at 75°C for 15 s, HHP at 500 MPa for 60 s, and UV‐C fluence of 69.2 mJ cm−2 was required to achieve the target 5 log CFU reduction of the test bacteria. Thermal treatment resulted in a significant (p &lt; 0.05) loss of enzyme activities (75.3% POD and 40.0% PPO), total phenolic content (TPC; 36.0%), vitamin C (27.4%), chlorophyll (12.4%), and negatively impacted the juice color. UV‐C treatment significantly (p &lt; 0.05) decreased the TPC of the juice and resulted in a 20.0% decrease in PPO activity. In comparison, HHP significantly (p &lt; 0.05) increased the chlorophyll content by 9.0% with negligible impact on the nutritive content, and PPO and POD levels. HHP would be preferentially selected over UV‐C and thermal treatment for wheatgrass juice based on changes induced by processing.Practical applicationsWheatgrass juice is a low‐acid health beverage that is marketed with the claims of high content of chlorophyll, antioxidants (phenolics and vitamin C), and enzymes (polyphenol oxidase and peroxidase) and distributed in frozen state. As a risk prevention control, a pasteurization step is required to achieve a 5 log CFU reduction of relevant pathogens. The study illustrated that HHP is the preferred treatment method for wheatgrass juice based on the negligible impact on product quality parameters and retention of nutritive composition while delivering the required microbial reduction. Although, the current study focused on wheatgrass juice the same equivalent treatments approach can be undertaken with other beverages when selecting the appropriate processing method to retain the raw characteristics of juices.

Effects of Drying, Lactic Acid, and an Antimicrobial Marinade on the Survival of Generic Escherichia coli on Biltong

ObjectivesThe objective of the experiment was to evaluate the effects of drying, lactic acid spray, and a certain marinade application on the survival of generic Escherichia coli on biltong.Materials and MethodsFrozen eyes of round (IMPS #171C) were obtained from a local beef purveyor. The eyes of round were thawed (at 4°C), trimmed of extra fat and connective tissues, and cut into strips (L × W × T; 6 in × 2 in × 0.75 in). The experiment was divided into 2 groups and replicated once. Experiment 1 was further sub-grouped into 3 treatments: (1) negative control (NC), (2) negative control for dip treatment (NCD), and (3) inoculated group (I). Experiment 2 was sub-grouped into 6 treatments: (1) negative control (NC), (2) negative control for dip treatment (NCD), (3) positive inoculated control (PIC), and inoculated treatments (4) marinated (M), (5) 2% lactic acid spray (LA), and (6) marinated and lactic acid spray (MLA). For both experiments 1 and 2, 12 strips of biltong were randomly selected for each treatment (n = 36 for experiment 1; n = 72 for experiment 2). The inoculated samples were dipped for 30 s in a cocktail (5-log) of 4 different strains of nalidixic adapted Escherichia coli (beef isolates) and allowed 2 h for attachment at 4°C. The lactic acid was sprayed to each side of the respective biltong and allowed a 10-min resting period. Marinade was applied to respective treatment groups by dipping, rubbing, and incubating overnight (at 4°C). All samples were kept in a smokehouse in a controlled environment with drying cycle at 78°F and 60% relative humidity. Experiment 1 was incubated in the smokehouse for a total of 12 d and experiment 2 was incubated for 9 d total. Samples from each treatment group were removed on Days 0, 2, 5, 7, 9, and 12 (experiment 1 only) for microbiological sampling and analysis. Samples were homogenized, serially diluted, enumerated on TSA plus 200 ppm nalidixic acid, and incubated at 35°C for 18–24 h. Colonies were counted after 24 h and colony counts were transformed into log10 CFU for reporting.ResultsThe data for experiment 2 showed that the treatments LA, M, MLA, and PIC were able to achieve a 2.5–3 log10 CFU reduction after 9 d of drying. The M and MLA treatments exhibited a 2–3 log10 CFU reduction after 2 d of drying as compared with LA and PIC that showed a similar reduction in microbial counts after 9 d of incubation. The NC and NCD treatment groups resulted in no microbial growth from Day 0 till Day 9 of incubation. The data for experiment 1 showed that there was a 1 log10 CFU reduction of E. coli in treatment group I. The NC and NCD groups did not show microbial growth from Day 0 till Day 9 of incubation. The water activity decreased overtime to 0.722 for experiment 1 and 0.711 for experiment 2. Overall, the M and the MLA samples appeared to have the greatest and quickest killing effect on generic E. coli.ConclusionResults from these experiments suggest that the combination of drying with a lactic acid spray and marinade application causes a decrease in the E. coli population on Biltong during incubation for 9 or 12 d. While the results show that there may be a small decrease from drying alone, the greatest decreasing effect appears to be the combination of the drying, lactic acid, and marinade. Future work will include additional replicates and experiments with pathogens such as E. coli O157:H7.

Rechargeable polyamide-based N-halamine nanofibrous membranes for renewable, high-efficiency, and antibacterial respirators.

Emerging infectious diseases (EIDs) have been acknowledged as a major public health concern worldwide. Unfortunately, most protective respirators used to prevent EID transmission suffer from the disadvantage of lacking antimicrobial activity, leading to an increased risk of cross-contamination and post-infection. Herein, we report a novel and facile strategy to fabricate rechargeable and biocidal air filtration materials by creating advanced N-halamine structures based on electrospun polyamide (PA) nanofibers. Our approach can endow the resultant nanofibrous membranes with powerful biocidal activity (6 log CFU reduction against E. coli), an ultrahigh fine particle capture efficiency of 99.999% (N100 level for masks), and can allow the antibacterial efficacy and air filtration performance to be renewed in a one-step chlorination process, which has never been reported before. More importantly, for the first time, we revealed the synergistic effect involving the intrinsic structure of polymers and the assembling structure of nanofibers on the chlorination capacity. The successful fabrication of such a fascinating membrane can provide new insights into the development of nanofibrous materials in a multifunctional, durable, and renewable form.

Validation of a Restructured Beef Jerky Product and Process to Reduce Pathogen Loads and Improve Shelf Stability in Ethiopia

ObjectivesAnimal-sourced foods (ASFs), such as meat, provide nutrients that are beneficial for physical and cognitive development, especially in developing countries. Despite Ethiopia containing Africa’s largest inventory of livestock, market structure and inefficiencies in livestock and meat industries contribute to low-per capita consumption of meat. The combination of extensive periods of fasting from ASFs, knowledge gaps in hygienic handling and sanitation, lack of infrastructure and preservation, and weakly enforced food safety regulations contribute food safety risks in an already protein-deficient population. The objective of this study is to develop a dried beef jerky procedure that will reduce pathogen loads in meat, improve shelf stability, and increase access to ASFs in Ethiopia.Materials and MethodsChallenge studies were performed to validate a restructured jerky production process for control of five serotypes of Salmonella enterica (Saint Paul, Anatum, Typhimurium, Newport, Dublin) and three strains of E. coli O157:H7, within the constraints of equipment and ingredients available in Ethiopia. A traditional Ethiopian spice mixture was added to lean ground beef (94% lean, 6% fat), and in separate trials apple cider vinegar and pureed raisins were incorporated at varying percentages of the overall weight. The ground meat mixture was formed into strips and dehydrated to achieve aw of less than 0.70 for shelf stability and samples were plated for enumeration before and after drying. A consumer taste panel was conducted with treatments (0% and 15% raisin inclusion) to determine the acceptability of Ethiopian consumers. Sixteen Ethiopian consumers (10 men and 6 women) were asked to answer study-related questions and evaluate jerky products on visual appeal, texture, off-flavor, and overall liking on a 10-point hedonic scale.ResultsVinegar inclusion negatively impacted log CFU reductions of S. enterica as the control demonstrated significantly higher (P = 0.04) reductions than treatments including vinegar at 0.5, 1, and 2%. Including 15% raisins (w/w) in the meat and spice mixture resulted in an increased (P < 0.0001) log CFU reduction of S. enterica (5.41 CFU/g) versus the control (4.44 CFU/g) and all treatments achieved greater than 6-log CFU/g reduction of E. coli O157:H7.ConclusionIncluding raisins reduces S. enterica loads versus the control and all formulations exceeded a 6.0 log CFU/g reduction of E. coli O157:H7, in a restructured beef jerky product. A restructured jerky product could provide butchers with an additional marketing avenue and opportunity to reduce waste and pathogen loads in beef. Ethiopian consumers would also have an option for a commercially available, shelf-stable product which could provide additional protein to their diet that is easy to store and transport.

Impact of photodynamic therapy versus ultrasonic scaler on gingival health during treatment with orthodontic fixed appliances.

Poor oral hygiene during treatment with fixed appliances results in plaque accumulation. The presence of bacteria in the gingival crevice triggers an inflammatory reaction in the gingival tissues. The aim of this study was to compare the impact of two preventive treatments, photodynamic therapy (PDT), and ultrasonic scaler (US), on gingival health in patients under fixed orthodontic treatment. Twenty orthodontic patients were randomly allocated to two groups: PDT or US. Each group received seven sessions [days 0, 15, 30, 45, 90 (3-months follow-up), 180 (6-months follow-up), 270 (9-months follow-up)] of experimental interventions, and clinical parameters [Plaque index(PI); gingival index(GI); probing depth(PD)], periodontopathogens [Agreggatibacter actinomycetemcomitans; Porphyromonas gingivalis; Prevotella intermedia; Micromonas micros; Fusobacterium nucleatum; Tannerella forsythia; Campylobacter rectus; Eikenella corrodens; Capnocytopaga sp.] and protein markers [IL-1β;IL-1ra;IL-6;IL-10;TNF-α;FGF-2/FGF basic] were monitored at baseline and at 3, 6, and 9 months. ANOVA, Student's t-test with Bonferroni correction and ANOVA with multiple rank test were used to identify differences between groups (P < 0.05). Clinical assessments [PI, GI, and PD] yielded no differences (P > 0.05) between groups, which showed a major decrease at the start of the trial. Reductions in total colony forming units (log CFU reduction) were observed with both treatments, although to a greater extent in the PDT group, but with no differences between groups (P > 0.05). Similar reductions in log CFU counts of P. gingivalis, P. intermedia, and F. nucleatum were observed in both groups (P > 0.05). The two groups also showed similar trends for inflammatory mediators with decreased levels of IL-1β, IL-10, and TNF-α, whereas IL-6 and IL-1ra levels remained stable and those of FGF-2 were increased after both interventions, with no differences (P > 0.05) between groups. Both PDT and US methods proved similar effectiveness for the treatment of gingival inflammation induced by fixed orthodontic appliances. Lasers Surg. Med. 51:256-267, 2019. © 2018 Wiley Periodicals, Inc.

Combined effects of garlic essential oil and allyl isothiocyanate against Escherichia coli O157:H7 in vitro and in pork sausage

ABSTRACT: Escherichia coli O157:H7 is a toxigenic serotype of E. coli and has been associated with foodborne outbreaks involving meat products, vegetables and fresh produces worldwide. Salts for curing are usually employed as antimicrobials in the production of pork sausages. However, salts do not have a significant inhibitory effect on enterobacteria. Due to the growing demand for natural foods, the use of essential oils has been proposed as natural antimicrobials in food. This study aimed to evaluate the effects of garlic essential oil (GO) and allyl isothiocyanate (AITC) against E. coli O157:H7 in vitro and in pork sausage. The Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) of these oils, alone and in combination, against E. coli O157:H7 were determined. Pork sausage was inoculated with 8log CFU/g E. coli O157:H7 and different combinations of GO and AITC. A control group was performed without essential oils. Sausages were packaged and stored at 6°C for 20 days. E. coli O157:H7 population and instrumental color (L*, a*, b*, C* and hue) determinations were performed at 5-day intervals. AITC showed lower MIC and MBC than GO. When combined, AITC and GO showed a synergistic effect. Treatments T3 and T4 showed 1,01log CFU and 1,87log CFU reduction of E. coli O157:H7 compared to control. The redness and the chroma of sausages treated with AITC and GO increased during storage. Together, GO and AITC caused minor changes in taste and flavor of sausages, and were able to reduce the population of E. coli O157:H7 and to maintain the red color of sausage during storage.

Activity of DNA-targeted C8-linked pyrrolobenzodiazepine–heterocyclic polyamide conjugates against aerobically and hypoxically grown Mycobacterium tuberculosis under acidic and neutral conditions

Mycobacterium tuberculosis (Mtb) is the aetiological agent of tuberculosis, the leading cause of death worldwide from a single infectious agent. Mtb is a highly adaptable human pathogen that might enter a dormant non-replicating (NR), drug-tolerant stage. Reactivation of dormant Mtb can lead to active disease. Antibiotic treatments of active and latent tuberculosis are long, complex and may fail to fully eradicate the infection. Therefore, it is imperative to identify novel compounds with new mechanisms of action active against NR bacilli. Dormant Mtb habitat is mostly thought to be the pH-neutral and hypoxic caseous granuloma. We have used the Wayne culture model to reproduce this environment and tested the activities of two DNA-targeted agents, C8-linked-pyrrolobenzodiazepine(PBD)-polyamide conjugates 1 and 2, against Mtb grown in aerobic and hypoxic conditions in both acidic and pH-neutral media. PBD 2 showed growth inhibitory activity at 5.1 µg/ml against 19-day-old hypoxic NR Mtb cultures with 1.8 log10 CFU reduction on day 21 at pH 7.3. PBD 2 was particularly effective against 5-day-old aerobic cells at pH 7.3, with CFU reduction (>6.8 log10) on day 21 at 5.1 µg/ml being identical to that of rifampin at 8 µg/ml. PBD 2 qualifies as a promising lead against aerobic and NR Mtb.

Enhanced viability of probiotics (Pediococcus pentosaceus Li05) by encapsulation in microgels doped with inorganic nanoparticles

The major reduction in probiotic viability that occurs during food storage and gastrointestinal transit limits their potential health benefits. Microencapsulation is one of the most effective methods to protect probiotics from various harsh conditions. In this study, a model probiotic (Pediococcus pentosaceus Li05) was encapsulated in an alginate-gelatin microgels in the absence and presence of magnesium oxide (MgO) nanoparticles (NPs). The morphology and surface properties of the encapsulation systems were characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM), which showed that both the probiotics and NPs were successfully incorporated into spherical microgels. The viability of the probiotic was evaluated after exposure to different conditions: long-term storage in an aerobic environment; heat treatment; and gastrointestinal transit. Encapsulation of the probiotics significantly enhanced their viability under these different conditions. Probiotics encapsulated in MgO-loaded microgels were more stable than free bacterial cells or those encapsulated in microgels alone: less than 2 log10 CFU reduction after 40 min incubation in gastric fluids versus 5 log10 CFU reduction in the first 10 min for free cells. The SEM images indicated that the NPs may lead to enhanced probiotic viability by filling pores inside the microgels, which may have inhibited the ability of oxygen and hydrogen ions to access the probiotics. Moreover, the MgO NPs neutralized the hydrogen ions in the gastric fluids, thereby reducing acid-induced degradation of the probiotics. These results demonstrate that MgO-loaded microgels may be a promising encapsulation and delivery system for improving the efficacy of orally administered probiotics by protecting them from the harsh conditions during storage and in the gastrointestinal tract.

Effects of combined high pressure (HPP), pulsed electric field (PEF) and sonication treatments on inactivation of Listeria innocua

Suspensions of non-pathogenic Listeria innocua ATCC 33090 in water were exposed to different combinations of high hydrostatic pressure (HPP), pulsed electric field (PEF) and sonication treatments. Treatments were conducted individually, or in various combinations – sequential HPP-PEF; sequential PEF-HPP, simultaneous HPP-PEF, sequential HPP-sonication and sequential sonication-HPP. The greatest reduction by an individual treatment was obtained with HPP, wherein exposure to 400 MPa for 100 s resulted in an 8 log reduction in CFU. Both PEF (30 kV, 10−3 s) and sonication (250s) treatments gave about 2 log reduction in the Listeria population. Sequentially applied HPP-PEF, and PEF-HPP treatments demonstrated mostly additive effects. Notably, however, a synergistic effect was observed when PEF and HPP were applied simultaneously. Combinations of HPP and sonication treatments demonstrated synergistic effects when HPP treatment was followed by sonication, but additive effects when sonication was followed by HPP. A relationship between Listeria innocua inactivation and increase in the suspension zeta potential was observed. However, protein content of the supernatant was found insignificant, indicating that leakage from cells were non-protein cell constituents.